One vertex per element, one color per generator, with an edge from x to x·s.
(9,10,13,16)(11,14,18,22)(12,15,20,24)(17,21,19,23)(25,26)(27,36)(28,37)(29,35)(30,32)(31,33)(34,38)(39,40)(1,2)(3,6)(4,7)(5,8)(9,10)(11,14)(12,15)(13,16)(17,21)(18,22)(19,23)(20,24)(25,27,31,30)(26,32,33,36)(28,35,38,39)(29,37,40,34)(1,3)(2,5)(4,8)(6,7)(26,33)(28,38)(32,36)(35,39) involution — undirected(9,10)(11,14)(12,15)(13,16)(17,21)(18,22)(19,23)(20,24)(25,28)(26,34)(27,35)(29,32)(30,39)(31,38)(33,37)(36,40) involution — undirected(1,3)(2,6)(4,8)(5,7)(9,11,13,18)(10,14,16,22)(12,19,20,17)(15,23,24,21)(25,29)(26,35)(27,34)(28,32)(30,37)(31,40)(33,39)(36,38)(1,2)(3,5)(4,7)(6,8)(9,12,13,20)(10,15,16,24)(11,17,18,19)(14,21,22,23)(25,30,31,27)(26,36,33,32)(28,39,38,35)(29,34,40,37)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.